question to simulation
From: Johanna Bernstein (johanna_bernstein_nospam_at_yahoo.com)
Date: Fri, 19 Aug 2005 02:25:03 +0200
I have again a smal question to the simulation-paradigma.
If I want to prove the security of a protocol using a simulator, which
on all publicly available input, can simulate the view of an adversary,
then I read in some proofs (e.g.  pp. 18 Theorem 4), that it is
allowed for the simulator to have access to an oracle, which for example
can decrypt ciphertexts or sign messages (encrypted with the public keys
or verified with the public keys used as input for the simulation). When
and why is it possible to use such an oracle, which can solve problems
for the simulator?
Thanks in advance for any help,